By taking a series of images, he hopes to “picture” different stages of drug-taking behavior—from the anticipation of getting the drug, through the experience of euphoria, or the “high,” and as the effect of the drug wears off.

“We have little idea what… causes a person to decide to engage in a rewarding activity, be it eating, sex, gambling or drugs,” Cowan explains. “We don’t know what parts of the brain are involved in the initiation of that activity.

“We’re hoping to find a part of the brain early on that gets activated before the experience of euphoria, that actually predicts that it is going to happen,” he says. “That might give us a target for therapy, or at least for further study.”

Functional magnetic resonance images show the brain of a study participant responding to an oral dose of amphetamine. The drug can produce the experience of a "high" or euphoria when taken in large doses. The images, of three different "sections" or view of the brain, detected changes in two different areas (top and bottom rows) over the course of about 90 minutes when the participant reported "positive" emotions on a mood scale. The blue color indicates deactivation of one brain region, while the orange spot indicates activation of another. While more detailed analysis is required to determine which specific regions respond to amphetamine, imaging studies like this are providing clues to the roles that different areas of the brain play in drug-taking behavior.

Courtesy of Ronald L. Cowan, M.D., Ph.D., and his colleagues at Vanderbilt and the McLean Hospital Brain Imaging Center in Belmont, Mass.